From: SIU Weather Processor (ldm@WEATHER3.ADMIN.NIU.EDU)
Date: Tue Oct 14 2008 - 23:37:18 EDT
AXPZ20 KNHC 150337
TWDEP
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED OCT 15 2008
TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM
THE EQUATOR TO 32N...EAST OF 140W.
BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.
...TROPICAL WAVES...
AN ILL-DEFINED TROPICAL WAVE LIES ALONG 100W FROM 8N TO 16N.
COMPUTER MODEL GUIDANCE DEPICTS WEAK LOW LEVEL CIRCULATION ALONG
AND UPSTREAM OF THE WAVE. STABLE CONDITIONS UNDER AN UPPER RIDGE
TO THE N OF THE RIDGE ARE INHIBITING CONVECTION NEAR WAVE N OF
11N...THOUGH ISOLATED MODERATE CONVECTION IS OCCURRING WITHIN
120 NM EITHER SIDE OF WAVE AXIS S OF 11N...POTENTIALLY FROM
LOW-LEVEL CONVERGENCE WITHIN ITCZ.
...ITCZ...
ITCZ AXIS IS CENTERED ALONG 08N77W TO 10N93W TO 08N113W TO
10N123W TO 08N140W. SCATTERED MODERATE CONVECTION WITHIN 120 NM
EITHER SIDE OF AXIS BETWEEN 80W AND 87W. SCATTERED MODERATE
CONVECTION WITHIN 180 NM S OF AXIS BETWEEN 92W AND 104W.
ISOLATED MODERATE CONVECTION WITHIN 90 NM S OF AXIS BETWEEN 119W
AND 123W. ISOLATED MODERATE CONVECTION WITHIN 90 NM EITHER SIDE
OF AXIS BETWEEN 132W AND 140W.
...DISCUSSION...
SUBTROPICAL RIDGE EXTENDS S FROM A 1031 MB SURFACE HIGH CENTERED
NEAR 40N137W TO NEAR 16N141W. ANTICYCLONIC SURFACE FLOW AROUND
THIS HIGH IS BRINGING W TO NW WINDS OVER NW PORTIONS OF THE
DISCUSSION AREA...WITH A TIGHTER PRESSURE GRADIENT CLOSER TO THE
SURFACE HIGH SUPPORTING SURFACE WINDS AROUND 20 KT FROM 14N TO
24N W OF 130W. THESE WINDS WILL DECREASE OVER THE NEXT DAY OR SO
AS THE PRESSURE GRADIENT SLACKENS. HOWEVER...A WEAK COLD FRONT
WILL APPROACH THE WESTERN CONUS COAST LATE THURSDAY...WITH
SURFACE PRESSURE RISES BEHIND THE FRONT CAUSING AN INCREASE
IN NORTHERLY WINDS ONCE AGAIN OVER NE PORTIONS OF THE AREA.
ACROSS THE REMAINDER OF THE AREA AT PRESENT...8 TO 10 FT SEAS
CONTINUE TO PREVAIL OVER AREAS SW OF A LINE FROM 30N120W TO
00N86W ACCORDING TO A RECENT JASON PASS. HOWEVER...AS THE LARGE-
SCALE PRESSURE GRADIENT DECREASES OVER THE REGION...WEAKER
SURFACE WIND FORCING WILL ALLOW FOR THESE SEAS TO DROP BELOW 8
FT OVER MOST AREAS.
OF CONCERN IS A GAP WIND EVENT OVER THE GULF OF TEHUANTEPEC. AS
A SURFACE RIDGE BUILDS BEHIND A LOW-LEVEL THERMAL BOUNDARY OVER
CENTRAL MEXICO...AND A BROAD SURFACE PRESSURE TROUGH PERSISTS SW
OF THE GULF...NW TO N SURFACE WINDS HAVE DEVELOPED OVER THE
GULF...CONFIRMED BY DATA FROM A RECENT QUIKSCAT PASS. THESE
WINDS ARE BEING FURTHER ENHANCED BY LOWER PRESSURE IN
ASSOCIATION WITH TROPICAL DEPRESSION 16 IN THE W CARIBBEAN. AS
SURFACE PRESSURES S OF THE GULF INCREASE THROUGH WEDNESDAY
...WINDS WILL SLACKEN SOMEWHAT BUT WILL INCREASE ONCE AGAIN BY
THURSDAY AS AN EVEN STRONGER RIDGE BUILDS S INTO CENTRAL AND S
MEXICO.
ALSO...STRONG NW SURFACE WINDS OF 20 TO 30 KT IN THE GULF OF
CALIFORNIA CONTINUE IN THE WAKE OF A SURFACE FRONT THAT HAS
PUSHED INTO NORTHERN MEXICO. AS PRESSURE RISES BEHIND THE FRONT
DIMINISH DURING THE NEXT 12 HOURS...THESE WINDS SHOULD GRADUALLY
DIMINISH...THOUGH SEAS OF UP TO 8 FT COULD PERSIST THROUGH
TONIGHT.
FINALLY...A 1011 MB SURFACE LOW IS CENTERED NEAR 11N125W WITH
ISOLATED MODERATE CONVECTION WITHIN 360 NM OF THE LOW CENTER.
THIS LOW IS EXPECTED TO DRIFT TO THE SW OVER THE NEXT DAY...WITH
STABLE CONDITIONS EXPECTED TO CONTINUE TO LIMIT CONVECTIVE
DEVELOPMENT WITH THIS SYSTEM.
$$
COHEN/KIMBERLAIN
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